2-Benzyl-4-phenyl-9,9a-dihydro-5,6-benzo-1 or 3-isoindolinones have been described by Klemm et al in J. Heterocyclic Chem., 9, 1215 (1972) as "N-benzylcyclolignan lactams", which are further examples of their "studies on the intramolecular Diels-Alder reaction". Surprisingly, it has been found that the 2-desbenzyl, or other N-substituted derivatives of said lactams, and reduced derivatives thereof, exhibit valuable pharmacological properties.